This invention relates generally to the field of product packaging, and more particularly to an improved tamper proof package, that is to say a package which will indicate the presence of tampering to a user upon a casual inspection.
The need for such packaging has been recognized for some time, and interest in such packaging has been heightened considerably by the prevalent alteration of nationally distributed proprietary pharmaceuticals with the intention of causig death or injury by unauthorized persons.
It is common practice to attractively package such items as aspirin and aspirin substitutes in a so called blister package which includes a fiberboard base and a synthetic resinous blister having peripheral edge portions which are sealed to the base. Such packaging is readily compromised by using a razor blade or other sharp instrument to cut the base at a peripheral edge, to reach the enclosed contents, and to reglue the cut edge. With care, the evidence of such activity can be adequately disguised.
Other expedients in the case of bottled products include the provision of a shrinkable collar which surround the screw cap of the container which must be torn or otherwise damaged before it can be removed from the neck of the container in order to open the cap. The material of which the collar is made can often be softened by heat, and again reshrunk upon the bottle without detection.
Still another attempted solution of the problem involves the use of a sensor containing a pH sensitive dye which displays a first color at normal atmosphere pH and a second color above normal atmosphere pH. An artificial atmosphere is introduced in the package which is released when the package is opened to change the color of the sensor. This method is, of course, inordinately expensive, and is justified only where the value of the contents of the container is high.